"""Helpers partagés par les routers CRUD.

`resolve_owned_ids`/`set_artists`/`set_wished_positions` sont utilisés à la
fois par `volunteers.py` (fiche éditée par la coordination) et `forms.py`
(vœux saisis depuis le formulaire public) — un seul endroit pour la
validation « ces ids appartiennent bien à cette édition »."""

import uuid

from fastapi import HTTPException
from sqlalchemy import delete
from sqlmodel import Session, select

from app.models import Artist, Position, VolunteerArtist, VolunteerPositionWish


def owned_or_404(instance, edition_id: uuid.UUID):
    """404 si l'instance est absente ou rattachée à une autre édition."""
    if instance is None or instance.edition_id != edition_id:
        raise HTTPException(status_code=404, detail={"code": "error.not_found"})
    return instance


def replace_links(
    session: Session, link_model, *, filter_column, filter_value, pairs
) -> None:
    """Remplace toutes les lignes d'une table d'association pour une clé."""
    session.execute(
        delete(link_model).where(filter_column == filter_value)
    )
    for row in pairs:
        session.add(link_model(**row))


def resolve_owned_ids(
    session: Session, model, edition_id: uuid.UUID, ids: list[uuid.UUID], code: str
) -> list[uuid.UUID]:
    """Ordre d'entrée conservé, doublons retirés ; 422 si un id est étranger."""
    wanted = list(dict.fromkeys(ids))
    if wanted:
        found = set(
            session.exec(
                select(model.id).where(
                    model.edition_id == edition_id,
                    model.id.in_(wanted),
                )
            )
        )
        if len(found) != len(wanted):
            raise HTTPException(status_code=422, detail={"code": code})
    return wanted


def set_artists(session: Session, volunteer, artist_ids: list[uuid.UUID]) -> None:
    ids = resolve_owned_ids(
        session, Artist, volunteer.edition_id, artist_ids, "artist.unknown"
    )
    replace_links(
        session,
        VolunteerArtist,
        filter_column=VolunteerArtist.volunteer_id,
        filter_value=volunteer.id,
        pairs=[{"volunteer_id": volunteer.id, "artist_id": aid} for aid in ids],
    )


def set_wished_positions(
    session: Session, volunteer, position_ids: list[uuid.UUID]
) -> None:
    ids = resolve_owned_ids(
        session, Position, volunteer.edition_id, position_ids, "position.unknown"
    )
    replace_links(
        session,
        VolunteerPositionWish,
        filter_column=VolunteerPositionWish.volunteer_id,
        filter_value=volunteer.id,
        pairs=[{"volunteer_id": volunteer.id, "position_id": pid} for pid in ids],
    )